Due to an increase in the number of cellular telecommunication systems because of upcoming next generation cellular telecommunication systems, two cellular telecommunication systems may have to be allocated to share at least partly the same radio resources, e.g. frequency. For example, if an operator cannot acquire new frequency spectrum to operate a new evolution of the third generation cellular telecommunication system, the new cellular telecommunication system has to be allocated to share the same frequency band with a current second generation cellular telecommunication system, such as GSM (Global System for Mobile Communications). For example, GSM typically uses a frequency reuse factor of three or higher and, therefore, frequency resources may be allocated to the GSM cells such that neighboring cells do not use the same frequency band. The new evolution of the third generation cellular telecommunication system may, however, be configured to use a frequency reuse factor of one, i.e. to use the same or overlapping frequency bands in all cells, which results in interference between the two cellular telecommunication systems. Accordingly, there is a need for controlling the interference to avoid losses in quality of service in the cellular telecommunication systems.